LONDON — For 20 very long seconds, Jessica Zelinka stood before a small group of writers just off the track of Olympic Stadium and she wept.

Zelinka wept for what went wrong in a heptathlon that fell hard off the rails in one event and a little more gently in another, more than enough to shove her off the medals podium she coveted and into seventh place.

She wept, too, for not having achieved her points goal of 6,600, a lifetime best that could have had her challenging for a medal.

In the end, it was a poor high-jump effort on Friday and a lukewarm long jump Saturday that undid Zelinka’s hopes.

Apart from that high jump, a brain cramp that drove her mad — for just a short while — and a long jump that never really unfurled, Zelinka had plenty to be proud of in London.

But maybe that will come into focus in time. For now, her vision was blurred by the tears she shed in the cold cement underground of a stadium.

“I don’t know what to make of it,” Zelinka said of her second Olympics, having finished fifth in Beijing four years ago.

“Five of the seven [events] were exactly what I wanted to do. I executed it — five out of seven isn’t bad. But heptathlon jumps are not forgiving at all. I could have messed up a throw, but jumps are not forgiving.

“I got a second chance after Day 1 but messed it up again with the long jump. It was over after that. There were just too many points. You can’t regain them by beating people by two metres in shot put or racing 10 seconds faster in the 800 [metres]. I don’t know how or why or what. I don’t know why I just couldn’t put a half-decent jump together for either of them. Just half-decent.”

Great Britain’s Jessica Ennis won the gold medal as she was expected to do, setting a national record of 6,955 points that left her 306 clear of German silver medallist Lilli Schwarzkopf. Russia’s Tatyana Chernova won bronze with 6,628.

Zelinka finished the competition with a fury, nearly chasing down Ennis in the home stretch of the 800. A season-best 2:09.15 was a half-second behind Ennis, around whom the British have promoted a good part of this Olympics.

“My time wasn’t great, but I ran hard,” Zelinka said. “I just wanted to run hard, knowing I wasn’t going to get a medal regardless.”

She had opened the competition Friday with a personal best of 12.65 seconds in the 100-metre hurdles, an event she’ll now prepare to run individually Monday and Tuesday.

The high jump was the pothole on her Olympic road, missing three times at 1.71 metres after clearing 1.65 and 1.68. But Zelinka hit her reset button during the afternoon break and returned to the track a very fired-up, motivated woman. First, she recorded a seasonal best 14.81 metres in shot put, then ran a personal best 23.31 in the 200 metres.

Zelinka went into the second day of the two-day contest clinging to the bronze-medal position by the narrowest margin, four points separating third from sixth.

She opened with a seasonal best in the long jump, leaping 5.91 metres that she knew could have been considerably more, then followed that with a career best 45.75 metres in the javelin.

That brought her to Saturday night’s 800 metres, along with 32 other athletes remaining from 39 entries.

The capriciousness of heptathlon, Zelinka said, is always part of its frustration — a strong event collapses one day, a weakness becomes a strength the next.

“But I prepared so well for this,” she said. “I didn’t see anything I was missing. We had some hiccups a couple weeks beforehand and training plans got switched last week. But all the work had been done to that point. Everything was in place.”

It was after Saturday’s javelin, the penultimate event, that Zelinka knew she’d neither win a medal nor achieve her points goal.

“After javelin, I just tried to stay focused,” she said. “After long jump, I went back and actually looked at the scores. What I saw was that I wasn’t going to be able to [get] 6,600. I was like, ‘Well, a medal isn’t going to happen and the 6,600 isn’t going to happen, either.”

Zelinka has one day off to try to clear her mind and focus on the hurdles, for which she qualified with a brilliant Olympic trials. Comparatively speaking, and not intending to minimize the discipline, she expects hurdles to be a breeze.

“It’s totally different in every way,” she said. “I’ve never been in an international [hurdles] competition. It’s all new to me and it’s going to be fun in that I go out there and run and not have to worry. It’s so … easy compared to heptathlon, I’m sorry to say. Even if I’m totally beat up, and I am, I’m just running for 12 seconds. I just need to focus for a period of time for two days straight.”

Zelinka had mostly dried her tears when she thought of her husband, Nathaniel, and their three-year-old daughter, Anika, who are in London with other family members to see her compete.

“I told Nathaniel I didn’t want Anika to come to the evening [athletics] sessions.” She said. “It was going to be packed, it’s late and would take two hours to get home afterward, past her bedtime. But right now I could really use a hug from her. It would be the best thing ever. She could have stayed up late, what was I thinking? But I’ll see her [Sunday] or after hurdles. I’m really looking forward to seeing her. I know she’s having so much fun right now that I’m not at all worried. I need her more than she needs me right now.”

And then Zelinka was led deeper into the stadium by a Games official, the inventory she’ll take of her puzzling Olympic heptathlon surely going to last well beyond this night.